Vertical distribution of tropospheric ozone in Antarctica and in the European Arctic

Ozone soundings performed since 1988 on the Antarctic Peninsula at Marambio (64.2°S, 57.7°W) and in the European Arctic at Sodankylä (67.4°N, 26.6°E), Bear Island (74.5°N, 19.0°E) and Ny Ålesund (78.9°N, 11.9°E) have been studied. Regular ozone soundings have never been made at these locations. A comparison of monthly mean tropospheric ozone profiles at high southern and northern latitudes has been made. In midwinter, differences between the monthly means in the northern and southern hemispheres are small, i.e. < 1 mPa. The general photochemical activation in springtime leads to larger differences: the partial pressures decrease in Antarctica whereas in the Arctic, pronounced production of ozone is seen. In spring and summer, the hemispheric differences are about 3 mPa. Exceptionally high and low partial pressures at Sodankylä and Marambio have been studied using 3-dimensional trajectories based on the ECMWF analyses. Episodes of upper tropospheric ozone loss at Marambio have been observed during the stratospheric ozone depletion period in spring. The only cause for especially high tropospheric ozone concentrations in Antarctica has been stratospheric intrusions. Low partial pressures in the boundary layer have been connected with advection of marine airmasses to Marambio. At Sodankylä, low boundary layer values have been observed during an advection from the Northern sea areas and also during the transport of airmasses from industrial source areas of Eastern Europe. Especially strong stratospheric ozone intrusion into the middle troposphere was observed at Sodankylä in September 1989. Partial pressures exceeding 7 mPa in the lower troposphere have been observed at Sodankylä during the summer in connection with the long-range transport of NOx/HC-containing air from Western Europe to Northern Scandinavia.